The present invention relates to a process for the preparation of hydrogen cyanide from crude acetonitrile. In particular, the present invention is directed to a process for the preparation of hydrogen cyanide from crude acetonitrile obtained as a coproduct during the manufacture of acrylonitrile by the Sohio Acrylonitrile Process.
Hydrogen cyanide is an important substance which is frequently employed as a starting material for various organic reactions. Its consumption is expected to increase in the future.
Currently, hydrogen cyanide has been manufactured mainly by the direct ammoxidation of methane (the Andrussow Process) and as a direct by-product of the ammoxidation of propylene to acrylonitrile (Sohio Acrylonitrile Process). In addition, various patents disclose descriptions of other processes for converting acetonitrile to HCN.
For example, U.S. Pat. No. 3,516,789 discloses a process for the manufacture of hydrogen cyanide by reacting acetonitrile free of HCN over an ammoxidation catalyst. The preferred procedure of this patent is a reaction of acetonitrile produced during the manufacture of acrylonitrile by recycling the acetonitrile which is free of HCN through the ammoxidation reactor over the ammoxidation catalyst. U.S. Pat. No. 3,911,089 discloses the preparation of hydrogen cyanide by addition of methanol to the ammoxidation reactor used during the production of acrylonitrile to further increase the yield of hydrogen cyanide. West German Patent 1,146,861 assigned to Bayer discloses hydrogen cyanide produced by the reaction of acetonitrile with molecular oxygen over an ammoxidation catalyst. This patent discloses that the yield of hydrogen cyanide is improved by the presence of ammonia. The processes disclosed in each of these patents have several disadvantages which are overcome by the process of the present invention.